Antibodies, or immunoglobulins, are proteins produced by cells of the immune system to identify and neutralize foreign substances, such as bacteria, viruses, or improperly proliferating native cells. An antibody consists of two larger “heavy” chain polypeptides and two smaller “light” chain polypeptides. Both the heavy and the light chain polypeptides contain a constant region and a variable region. It is the variable region that allows each antibody to specifically recognize a different target (i.e., antigen). The recognition of a foreign antigen by a specific antibody allows other parts of the immune system to recognize and attack the foreign antigen. In addition, an antibody can directly neutralize a bacterial or viral cell by binding to a part of the bacterial or viral cell that is needed for infection.
Antibodies are useful both for therapeutic and diagnostic functions. For example, anti-Rhesus factor D (anti-RhD) antibodies are regularly given as a prenatal therapy to mothers who are Rhesus factor negative (Rh−) to prevent the mother's body from attacking the Rhesus factor positive (Rh+) cells of a baby that she is carrying. Antibodies also are currently being used for a number of other therapeutic applications, such as for the treatment of rheumatoid arthritis, multiple sclerosis, psoriasis, transplant rejection, cardiovascular disease, inflammatory diseases (e.g., autoimmune-related disorders), respiratory syncytial virus infections, macular degeneration, and many forms of cancer including non-Hodgkin's lymphoma, colorectal cancer, head and neck cancer, chronic lymphocytic leukemia, and breast cancer. Some immune deficiencies, such as X-linked agammaglobulinemia and hypogammaglobulinemia also are treated with antibodies. In addition, antibodies are used to detect bacterial or viral infections or to detect which particular allele of a protein is being produced by a patient.
The manufacture of therapeutic and/or diagnostic proteins such as antibodies, is an expensive process. Companies using recombinant techniques to manufacture these proteins are working at capacity and usually have a long waiting list to access their fermentation facilities. What is needed, therefore, is a new, efficient, and economical approach to make antibodies in vitro or in vivo.